Enhanced Device Characteristics of Hybrid-Channel (Poly-Si/IGO) Structures with Ga2O3 and Al2O3 Interlayers by Suppressing Oxidation-Induced Variability for Ultra-High-Density 3D NAND Flash Memory Applications

Abstract

Hybrid-channel (HC) structures integrating polycrystalline silicon (poly-Si) and oxide semiconductors offer a promising path toward high-mobility, thermally stable architectures for next-generation 3D NAND flash memory. However, high-temperature annealing required for oxide crystallization often induces interfacial oxidation, leading to device variability and degraded performance. To address this challenge, this study proposes a novel HC structure incorporating an ultrathin interlayer of Ga2O3 or Al2O3 between the poly-Si and In-Ga-O (IGO) channels. This interfacial layer effectively suppresses poly-Si loss and the formation of non-uniform interfacial oxide, reducing poly-Si degradation from 5 to 1.7 nm and interfacial oxide growth from 7.4 to 2.5 nm. As a result, threshold voltage variation improves significantly, from +/- 0.45 to +/- 0.24 V and +/- 0.40 V for Ga2O3 and Al2O3, respectively, while average cell current density increases from 1.87 to over 2.0 mu A mu m-1. Memory windows expand accordingly, and both interlayers enable a field-effect mobility exceeding 100 cm2 V<middle dot>s-1. These findings demonstrate the importance of interfacial engineering in HC devices and establish a viable route for integrating thermally stable oxide semiconductors into ultra-high-density 3D memory applications.